Rain barrels help watersheds by reducing storm water runoff, which carries pollutants like oil and sediment into local waterways. By capturing rainwater, rain barrels prevent this runoff from overwhelming storm drains and streams, which helps reduce flooding, erosion, and pollution. They also conserve water by collecting free, untreated water for non-potable uses like garden irrigation. 
How rain barrels help

• Reduce pollution: Rain barrels capture runoff from rooftops that would otherwise carry pollutants like pesticides, fertilizer, oil, and sediment into storm drains and eventually into rivers and lakes.
• Lessen flooding: By collecting and holding rainwater, rain barrels decrease the volume of water that enters storm sewer systems, which reduces the risk of flash flooding in the area.
• Decrease erosion: Reduced storm water runoff helps prevent erosion in streams and riverbanks by decreasing the force and volume of water flowing into them.
• Conserve water: Rain barrels provide a free source of water for non-potable uses like watering lawns and gardens, which reduces the demand for treated tap water and saves money on water bills. This also saves energy-intensive treated water for drinking and other essential uses.
• Recharge groundwater: When rain barrels are emptied slowly, water can soak into the ground, helping to replenish groundwater supplies. 
  

You can buy a rain barrel and install it. Or, you can build your own.  if you choose to purchase, some tips are to choose a color and design that fits your landscape and home. There are also a few features you can look for: A debris screen keeps leaves, animals and insects (including mosquitoes) out of the barrel. A flat-back barrel fits close to your home, so the barrel is farther out of the way.

1. Prepare the Barrel
Thoroughly clean the inside of the barrel with a mild detergent or a bleach-and-water solution and rinse well to remove any residue or plastic shavings.

2. Drill Holes for Spigot and Overflow
Spigot hole: Drill a hole near the bottom of the barrel, about 2–3 inches up, to allow space for sediment to settle below the outlet and provide clearance for a watering can. The hole size should match the spigot fitting (e.g., a 15/16" hole for a 3/4" spigot).
Overflow hole: Drill a hole near the top of the barrel, on the opposite side from where it will connect to the downspout, to redirect excess water away from your home's foundation. The size will depend on your overflow fitting (e.g., 1" to 1.5" or 2" is recommended).

3. Install the Spigot
Apply waterproof sealant or wrap the threads of the spigot and the bulkhead fitting with Teflon tape.
Insert the fitting into the spigot hole, ensuring a rubber gasket or washer creates a watertight seal on the inside or outside of the barrel, depending on the fitting design. Tighten securely with pliers, being careful not to over-tighten and damage the plastic.

4. Install the Overflow
Attach your overflow adapter or pipe into the top hole, using sealant or a washer as needed to ensure a tight seal.
Attach a hose to the overflow fitting and direct it to another rain barrel, a rain garden, or a distant area away from your foundation.

5. Prepare the Top Opening
If your barrel has a sealed top, cut a large hole using a jigsaw, leaving a 1-inch rim. If using a lidded garbage can, cut a hole in the lid for the downspout connection.
Cover the opening with a fine mesh screen to filter debris and prevent mosquito breeding. Secure the screen with staples, a bungee cord, or by placing the lid over it, trimming any excess material.

6. Position and Install the Barrel
Choose a stable, level location under a downspout and build a raised platform with cinder blocks or a sturdy stand. Elevation provides the necessary water pressure for a hose or watering can.
Measure and cut your downspout so that it aligns with the entry hole on your barrel lid or install a downspout diverter according to the manufacturer's instructions.

7. Test the System
Wait for rain and check your system for leaks. Ensure water flows correctly into the barrel and the overflow system works as intended. 

Rain Barrels: Small Investment, Big Benefits
In this video, you will learn about the great dollar and environmental benefits of Rain Barrels; a simple and effective investment to conserve water, save money, and help the environment from the US Environmental Protection Agency.

Build Your Own Rain Barrel
A student's guide to building a simple rain barrel from the Chesapeake Bay Foundation. 

Rain Barrel Maintenance Guide
Another rain barrel resource from the Chesapeake Bay Foundation.  

How to Make a DIY Rain Barrel in 5 Easy Steps
Better Homes & Gardens article offers guidance to transform an outdoor garbage can into a resource-saving DIY rain barrel with these easy instructions on how to make a rain barrel for your yard. 

Soak Up the Rain: Rain Barrels   
Information and resources from the Environmental Protection Agency (EPS) on rain barrels.